.login {
    width: 400px;
    height: 400px;
    background-color: rgba(255, 255, 255, 0.8);
    margin-left: 700px;
    margin-top: 200px;
}

.login .row {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 50px;
}

.login h3 {
    padding: 50px;
    text-align: center;
    font-size: 30px;
}

.login span {
    display: block;
    width: 100px;
    font-weight: 700;
}

#username ,#password {
    border: none;
    width: 200px;
    height: 30px;
    /* 选中对话框后不会有黑色边框线 */
    outline: none;
}

#submit {
    width: 300px;
    height: 40px;
    background-color: green;
    border: none;
    color: white;
    border-radius: 5px;
}

#submit:active {
    background-color: grey;
}

